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dtech
on July 21, 2023
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Nanosecond timestamp collisions are common
I feel like v7 is almost a strictly better v4. Assuming you can generate a v7 (you have a time source), what are the disadvantages?
andersa
on July 21, 2023
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Anyone who can see the uuidv7 can determine at what time it was generated. You might not want that for things exposed to users.
wolf550e
on July 21, 2023
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You can hand out uuidv4 to clients without revealing anything.
madsbuch
on July 21, 2023
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Entropy. You loose bits to a known source, which reduce entropy of the UUID.
dtech
on July 21, 2023
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I do feel 74 bits per second is enough though. That would require 2^(74/2) = 137 billion UUIDs generated in a single second for a 50% chance of a single collision.
dralley
on July 21, 2023
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128 bits is a lot of entropy to go around, though.
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